PTL 1 discloses a storage system including a plurality of microprocessors and configured to prevent load concentration on one microprocessor in the following manner. Specifically, when one of the plurality of microprocessors performing an I/O process for a received I/O request has a load heavier than a first load, the microprocessor allocates at least an I/O process part of the I/O process to any of the other microprocessors and the other microprocessor performs at least the I/O process part (the I/O process part is a process part including a cache control process involving reserving one area of a cache memory 20, i.e., a cache area for storing data in the cache memory 20).